Steam boiler



' 29. J. A. PILCHER ET AL 1,737,385

5 TEAM BOILER Filed April 2 1925 3 Sheets-Sheet 1 imiuijliii ilwiiil IIIIII II! INVENTORS John A. l lchmranmac. \h or ATTORNEY Nov. 26, 1929. J.A. PILCHER ET AL 5 STEAM BOILER File April 24, 1925 3 Sheets-Sheet 2 JohA. Darn-bargaiw..- ATTORNEY Nov. 26, 1929. ,1. A. PILCHER ET AL1,737,385,

STEAM BOILER Filed April 24, 1925 3 Sheets-Sheet 5 o INVENTORS Jd-m A.Pflehem' John A. Doarnbc-raar "The-u" ATTORNEY Patented Nov. 26, 192?:

JOHN A. PILCHER Ann Jenn A. nonnnennenn, or ROANOKE, vraem m STEAMBOILER A plication niean rir 24., 1925. Serial m. 25,514..

This invention pertains to steam boilers and has among its objects,,toprovide improved means for the securing and bracing of certain of theboiler sheets relative to each other. H

In steam boilers, as in. all pressure 0011- tainers, it is necessarythat means be provided for the bracing of flat surfaces, so that theforces acting on these flat surfaces may be transferred to some otherpart of the boiler, which is stronger and more suitable for absorbingthem. In steam boilers of the locomotive type, the principal sheets forwhich this bracing must be provided, are

the front and the back flue sheet and the crown sheet. I r I In a boilerof the locomotivetype, the main bracing of the flue sheets are the flueswhich are secured to and extend fromthe front to the back flue sheet,thugs displacement of the two sheets due to internal pressure islimited; However, on account of the firebox, which is located at oneend, it is necessary in the construction of a locomotive type'boilerthat the front flue sheet be larger than the backflue sheet. Thisproduces alarger load on the front flue sheet than on the back, andWhereas the flues may be approximately uniformly distributed over theback flue sheet,

they cannot be so distributed over the front flue sheet. Therefore inaddition to theflues, braces are provided which transfer a part of theload onthe front flue sheetto the barrel of the boiler. Even with thisa'd-di tional bracing on the frontflue sheet, which can seldombeuniformly distributed, it has been founddiflicultin practice toprevent movement of the front flue sheet with respect to the barrel ofthe boiler. Any movement of the front flue sheet causes the back fluesheet to move also, as the two sheets are secured to each other by meansof the flues. Any movement of the back flue sheetcaused by forcestransmitted to it through the flues and by internal pressure, willproduce high stresses at certain parts of its outer edge where it issecured to other sheets of the boiler.

lieved a sufficient number of times, they will If these stresses are setup and re-' finally result in the'cracking. of the flue sheet andthereby cause its renewal or repair.

Another part of a locomotive boiler where it has been found byexperiment that high stresses are set up, is in the top of the crownsheet near. where it is-"jloi'ned to the back flue sheet. I The outsidewrapper or barrel sheet over the front end of the crown sheet usuallyhas a smaller radius of curvature than that portion of the crown sheetunder it, and while the two are secuif ed to each other, thereis onaccount of unbalanced forces, a move-- ment of the crown sheet relativeto thewlap per or barrel sheet. This movement, whicl'i has been recordedin experiments, isismau, but if repeated a suflieient. numberof timeswill eventually. cause the failure of theftopj of the crown sheet nearwhereit is secured to the back fluesheet. I r

The object of this inyention is to pro """de suitable means wherebyhighstresses are slim. in'ated at or near the; line ofiu'nctioii or two ormore sheets of the boiler WVith the foregoingpbject in iew; theinvention consists of the formation, coinbina-tio'nand arrangement ofparts" as set forth,- particularly in the appended claims, the variouselements being. co ordiiiated to produce improvements generally in thisart. In the drawings,- Fig'. l is afragmentary longitudinal sectionalview of a boiler'of thelocomotivetype. g p f h Fig. 2,-is a sectionalview taken apprenmately on line 22.0f Fig, 1-, showing. how the fluesand braces are'located on the front flue sheet.-' A, I Fig. 8 isafragmentary sectionalview taken approximately on line 3 3 oflFig. 1'.

Fig. 4c is an enlarged view showing how our brace is applied to thejunction of the crown sheet. and the back flue sheet.

Fig. 5 is a View showing how ourbrace may be applied when theback fluesheet is buttqvelded to the} crown sheet.

, Fig. 6 is a viewtak'en approximately on line of Fig. 5;- e I Fig. 7-is an enlarged fragmentary sectional view of a boiler showingthe methodof applying our brace to the junctio rof the crown and back fluesheet,,-when the back 1 9-9 ,of Fig. 8.

Fig. 10 is an enlarged View taken on line 10--10 of Fig. 8.

Referring to these drawings which show one embodiment of our invention,the front flue sheet 1 is attached to the barrel 2 by ,means of therivets 3. The back flue sheet l is weldedto the combustion chamber 5,the top of which is known as the crown sheet 6, at 7. The flues 8 aresecured to and extend a from the front flue sheet to the back fluesheet. It will be noted that while the flues 8 ma 'beevenly distributedover the back flue s eet, there is a portion of the front flue sheetwhich is not provided with flues, and while this portion is braced bymeans of the braces 9 which extendto the barrel of the boiler, it isvery difficult to prevent movement of the front flue sheet with respectto the barrel sheet.

It will be readily seen that movement of the front flue sheet will causethe back flue sheet to move also, as the two sheets are tied together bymeans of the flues 8. This movement if repeated a suflicient number oftimes,

i will cause the back flue sheet to crack in the flange knuckle at alocation between the top row of flues and where it is joined to thecrown sheet as shown approximately at 10.

In order to reinforce the back flue sheet where this failure wouldoccur, we have provided the brace 11, which is secured to the crownsheet 6 and the back flue sheet l, by means of the welding 12. Thesebraces 11 may be applied along the top of the crown sheet for a distancesuflicient toprevent the failing of the crown and the back flue sheet.These braces 11 not only eliminate high fiber stress in the back fluesheet at or near the line of junction of the flue sheet and the crownsheet, but will also eliminate high fiber stress in the crown sheet ator near the line of junction of the two sheets. The braces 11 may beapplied all the way around the back flue sheet if found necessary,although the failure of the flue sheet usually occurs at the top andbottom rather than at the sides.

Figures 4 and 5 are enlarged views showing how our brace 11 maybeapplied when the back flue sheet is flanged and welded, or

when it is butt-welded to the crown sheet. Brace 11 may be readilyattached to the crown sheet and back flue sheet by welding as shown at12 in Fig. 6. It will be noted that the braces 11 are carried back onthe crown sheet close to the stay-bolts 13 and are carried down on theflue sheet close to the top of the flues 8. It will also be noted inFig. 6, that the brace 11 may be of a bulb sheet beyond thevline ofjunction of the two sheets with an additional row of stay-bolts and withthe brace 11, will make the junction of the two sheets very strong andremove the possibility of failure of either sheet near their unction. 71

In Fig. 8, the crown sheet 6 and the flue sheet 4 are crimped near wherethey are joined together as shown at 14:. The crown sheet and flue sheetare cut to fit this crimp.- ing and the two are welded together as shownat 7 in Figs. 9 and 1O.v With this method of securing the two sheets toeach other, the brace may be omitted, as the crimping will providesufficient stiflness and transfer the high stresses away from thejunction of the two sheets. I

Having described our invention, what we claim is:

1. In a steam boiler, the combination of a flue sheet and a crown sheet,means rigidly securing said sheets to each other; said means includingbracing'means disposed at intervals on the water side of said sheets andin planes substantially at right angles to the planes of the saidsheets, said bracing means bridging the junction line and acting toinsure against relative movement of the adjoining portions of the saidsheets.

2. In a locomotive steam boiler, the combination of a back flue sheetandfireboxsheets rigidly secured thereto, said fire box sheets beingdisposed in planes substantially at right angles to said back fluesheet, bracing means disposed at intervals on thewater side of saidsheets in planes substantially at right angles thereto, said bracingmeans bridging the junction line of said sheets to insure againstrelative movement of the adjoining portions of said sheets.

JOHN A. PILCHER. JOHN A. DOARNBERGER.

